The singer played a fundraiser in New York on Wednesday night and said Clinton was the best person to lead America.
"I never cease to be amazed at the misogynistic attitude of some people in this country. And I say to hell with them," Elton said.
"The reason I'm here tonight is to play music, but more importantly as someone who comes from abroad, and is in America quite a lot of the time (and) is extremely interested in the political process because it effects the whole world."
"I've always been a Hillary supporter," he added.
A New York senator and wife of former president Bill Clinton, Hillary is currently trailing Illinois' Barack Obama for leadership of the Democratic party.
A member of Clinton's staff said that the event had raised $2.5 million (£1.26 million) for her campaign.